Fuel pump external leak, do not let this happen to YOU!!

[Mogman]

Most guys that have been twisting wrenches for 50 years would not admit to this stupid but simple mistake.
But if it saves anyone else from the grief I am about to go through so be it..

A few months ago I replaced a fuel pump with an external leak, I had been waiting for the excuse to install an electric pump anyway.

What I missed was it had filled the right two gear hubs with diesel and now they are very unhappy as the inspection of the magnetic drain plugs reveal. (basically if there is anything more than just "mud" on the magnets you have problems)

So there you go, bad fuel pump check/drain/refill all your gear housings and also check the transmission and TC case.

 

[mgFray]

How did it get into the hubs? Vent lines connected in a normal case, or is this something related to the deep water fording?

 

[Mogman]

How did it get into the hubs? Vent lines connected in a normal case, or is this something related to the deep water fording?

No DWF gear just pumped through the vent lines.
Edit, would have the same potential problem if the truck had DWF

 

[juanprado]

Did you find a lot of debris on the magnets?

 

[Mogman]

Did you find a lot of debris on the magnets?

Yes, like med/course sand, spread it on a rag and when the oil is absorbed you can clearly see the bits of steel.

 

[Action]

Newer (turbo) hmmwv fuel vent lines do not connect to the other vent lines. The fuel pump vent runs back to a “T” on the filler neck.

 

[juanprado]

Yes, like med/course sand, spread it on a rag and when the oil is absorbed you can clearly see the bits of steel.

Keep us posted on what you find when you tear into it. Where you getting any noise or grinding? What made you check?

 

[Mogman]

Keep us posted on what you find when you tear into it. Where you getting any noise or grinding? What made you check?

Shortly after replacing the pump I installed the 6L80 transmission, the vent system was not "complete" until later when I installed the GEP turbo, at that time I took the tee that was on the old fuel pump out of line and installed it for the 6L vent as it had a 5/16 rubber vent hose and that worked out perfectly.
Once the vent system was complete it started pumping a small amount of gear oil into the air filter housing which drained out of the drain valve.

 

[Mogman]

Keep us posted on what you find when you tear into it. Where you getting any noise or grinding? What made you check?

Actually I have a set of used 12K hubs and new half shafts for the DuraVee that I was on the fence whether or not I was going to install.

So the plan now is to go through/rebuild the 12K hubs, install them on the DuraVee then install 2 of the pulled 10K hubs on the Detroit.

Meanwhile just keep a close eye on the Detroit and try not to get too far from home, I do have to make a 100 mi round trip in the morning to the ol muffler shop that installed a 2 1/2" pipe as a muffler delete on a 3" system, what a bunch of bozos, I could have and should have done a better job with a 3" 90 and some pipe, but thought those guys could do a better job, of course they are not big on letting you into the shop so I did not notice until I get home and put it on the lift...

Oh yeah, they removed the three bolts holding the body mount and the muffler and did not replace them.....

It's ALWAYS something!

 

[Mogman]

Well they were very happy to re-do the exhaust although the request for a $50 refund for fuel costs just got me a stare.
So after a 50 mile run at 65-70 MPH the wheel hubs were 117, 133, 127 and 121 degrees the 133 and the 121 were the "damaged" hubs the 117 and 127 were the other side so I do not think I am in any immediate danger of failure

 

[nikojo]

Thanks for sharing this painful story.

I’m not informed enough to understand how this happened. How can we prevent this??

Was it the electric fuel pump? Something about the pressure? What would you have done differently?

Thanks again.

 

[Mogman]

Thanks for sharing this painful story.

I’m not informed enough to understand how this happened. How can we prevent this??

Was it the electric fuel pump? Something about the pressure? What would you have done differently?

Thanks again.

All HMMWVs except possibly the later Turbo models (Action said) have the body of the fuel pump plumbed into the gear box/transmission/transfer case vent system, to say all the gear boxes (geared hubs and differentials), transmission and transfer case are all tied together in a common vent line) the bad fuel pump simply pumped fuel out into the vent lines to the geared hubs.

This would not happen with an electric pump or a civilian mechanical pump without the vent connection.

I would not worry about it unless you have a leaky pump, a rise in motor oil level or oil coming out of the air filter area, the vent system is terminated at the air filter.

When I installed the 6L transmission I had broken the vent system integrity until I found the fitting I needed to add the 6L to the vent system, otherwise I probably would have had the oil coming out of the air filter area soon enough to avoid this problem.